Graphic design is actually the art and process of combining text and graphics to communicate an effective language in the design of logos, brochures, newsletters, posters and in fact, any type of visual communication. This is achieved by using the elements and principles of graphic design.
Always keep the design and layout of the graphic design as simple and clean as possible, as the more cluttered it is, the more difficult it is for the customer to find the important stuff! When using colors in your graphic design, it is better to use colors from your set of corporate colors. This is because you should present consistency in all your advertisement media, so that people will know how consistent you actually are! Never use all the colors of the rainbow in one design as this only confuses the customer. Perhaps 2 or 3 colors form your corporate color should be enough for your design!
There are tons of free fonts found in the Internet to incorporate in your graphic design. However, it is not always that you can use all of them. Use a single font for the content of your design, and if required, you could use a different, like a bolder and louder font, for the headings...